1. Field of the Invention
The present invention relates to a roller hemming method for folding, by a working roller, a flange that is erected from a workpiece, as well as to a hemmed member.
2. Related Art
A roller hemming apparatus for hemming a workpiece by a working roller is known.
The roller hemming apparatus is configured so that an arm of a robot is provided with a working roller and the working roller can be moved along a flange of a workpiece by moving the arm in three-dimensions.
In order to hem the flange of the workpiece by the roller hemming apparatus, first, a locus along which to move the working roller is determined by teaching (follow operation). Information of the thus-determined locus is stored in a control section of the robot.
After the locus information has been stored, the workpiece is placed at a working position. The working roller is moved on the basis of the locus information in a state that the workpiece is placed at the working position.
The working roller is moved along the flange in the state that the working roller is pressed to the flange.
As described above, the hemming method is known in which locus information is obtained in advance by teaching and a flange of a workpiece is folded so as to be brought into contact with the main body of the workpiece by moving a working roller along the flange by controlling the robot on the basis of the thus-obtained locus information (refer to JP-A-05-305357, for example).
It is preferable that the tip of the flange be kept in contact with the main body of the workpiece even after the flange is folded so as to come into contact with the main body of the workpiece.
When the flange is folded by the working roller, the flange is folded at its base end. However, the flange tends to be inclined slightly in such a manner that its distance from the main body of the workpiece increases as the position goes from the base end to the tip. That is, the tip of the flange tends to be separated from the main body of the work.